JPH0582307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Use The present invention relates to a thermal transfer color recording device capable of multi-gradation printing, which can be applied as a hard copy device in the field of computer graphics, new media fields such as video systems, and communication fields such as facsimile machines. It is related to.

BACKGROUND OF THE INVENTION In recent years, improvements in integrated head manufacturing technology, including thermal printers, have led to the development of color printing using thermal heads that have simplified device configurations and are capable of high-speed recording.

FIG. 1 shows an example of the configuration of a recording portion of a general thermal transfer recording device capable of printing gradations.

Reference numeral 1 indicates a pulse width conversion unit that determines the energization time to the thermal head and outputs thermal head drive data b in order to record on the recording medium at a predetermined density based on the input gradation data a, and 2 indicates a plurality of gradation levels. The thermal head has a heating resistor for recording and its driver, and 3 is a fixed output power source that applies a heating voltage to the thermal head heating element.

FIG. 2 shows the difference in coloring characteristics of ink sheets A and B when a fixed voltage is applied according to the example of FIG. 1, where the vertical axis represents recording density temperature and the horizontal axis represents current application time.
In general, multi-color ink sheets have different coloring characteristics.

V _A and V _B are the characteristics of the respective ink sheets A and B. To simplify the explanation, the saturation recording density D _MAX of each ink sheet is the same, and the energization time to reach D _MAX is the respective characteristic. _tAMAX ,
_tBMAX .

Figures 3 and 4 show the recording paper base density and saturated recording density when not printing using the ink sheets A and B.
The energizing pulse width range when dividing D _MAX by a predetermined number of recording gradations (8 in this example) into 9 gradations including the recording paper base paper density is determined by the relationship between the minimum number of divided pulses and the recording density. It shows. D _W is the unit gradation density width that ensures the number of recording gradations, and t _WA and t _WB are the minimum divided pulses corresponding to the unit gradation density width D _W when recording with ink sheets A and B, respectively. In this example, it is assumed that ink sheet B has lower coloring characteristics, and is shown as t _WB =2t _WA .

T′ _AMAX and T′ _BMAX are the pulse widths at which the respective saturation concentrations are reached.

As shown in Figure 2, since the color development characteristics of multiple color ink sheets are different, in order to ensure the recording gradation, multiple colors can be printed using the narrowest pulse width t _WA among the minimum divided pulse widths of multiple color ink sheets. Since recording is performed on all sheets of ink sheet recording, when recording on ink sheet B, which has low color development characteristics, the pulse width T′ _BMAX required for saturation density recording is long, and the minimum pulse width T′ Since division is performed using the energization time of the minimum divided pulse width t _WA , which is narrower than the divided pulse width t _WB , the minimum total number of divided pulses required to record the saturation concentration increases (in this example, it has doubled). The total number of pulses in the pulse width converter increases, making the circuit and memory configurations more complex, which is disadvantageous in terms of data transfer speed to the thermal head, and the recording time for each color is different. It had some flaws.

The present invention solves the above problems by making the voltage application time corresponding to the image density to the heating element of the thermal head the same for any color, simplifying the circuit configuration and memory configuration, and achieving inexpensive thermal transfer color recording. The purpose is to provide equipment.

Means for Solving the Problems In order to achieve this object, the present invention provides voltage changing means for changing the voltage applied to the heating element of the thermal head depending on the color of the ink to be printed, and a method for printing by the thermal head. pulse signal generation means for generating a signal for determining the voltage application time to the heating element of the thermal head in accordance with the desired pixel density at the same time for each color, and a signal generated by the pulse signal generation means. The voltage from the voltage changing means is applied to the heating element of the thermal head for a period of time determined by .

Effect With the above configuration, the voltage application time corresponding to the image density to the heating element of the thermal head can be made the same for any color, and the respective current application time to reach the recording saturation density on each ink sheet can be made the same. It becomes possible to make the minimum total number of divided pulses the same. As a result, the total number of pulses handled by the pulse width converter to ensure a predetermined gradation becomes the minimum necessary, the circuit configuration and memory configuration of the pulse width converter can be simplified, and an inexpensive device configuration is possible. By reducing the total number of minimum divided pulses, the amount of drive data transferred from the pulse width converter to the thermal head is reduced, the data transfer time is shortened, and high-speed transfer is possible. By making the recording time of an ink sheet with a long maximum recording time almost the same as the recording time of an ink sheet with a short maximum recording time, it is possible to provide a thermal transfer color recording device with multiple gradations capable of high-speed recording.

Example FIG. 5 shows an embodiment of the present invention.

1 is a pulse width converter, 2 is a thermal head, a
is the input gradation data, and b is the thermal head drive data, which are the same as shown in FIG. 4 is a variable output power supply, 5 is a power supply control section,
This power supply control unit 5 controls the output voltage between terminals c and d of the variable output power supply 4 to be applied to the thermal head 2 according to the unit gradation density of the ink sheets A and B based on ink sheet information e of a plurality of colors. A power supply control signal is output that makes the respective minimum divided pulse widths t' _WA and t' _WB corresponding to the width D _W the same.

Figures 6 and 7 show the color development characteristics in relation to recording density and current pulse width or minimum number of divided pulses in an embodiment of the present invention using ink sheets A and B shown in Figures 3 and 4. V _A ″, V _B ″ are shown. here
t″ _AMAX , t″ _BMAX are the current pulse widths at which the recording saturation density is obtained with each ink sheet, and t′ _WA ,
t' _WB is the minimum divided pulse width corresponding to the unit recording density width D _W that ensures the required gradation of each ink sheet A, B, and by controlling the voltage applied to the thermal head 2, t' _WA , t' _WB becomes. As a result, the saturation density recording pulse widths _t''AMAX and _t''BMAX are almost the same, so the minimum total number of divided pulses up to the _t''AMAX and _t''BMAX can also be made the same, respectively. The required number of gradations can be secured for each ink sheet, and the pulse width can be converted using the minimum necessary number of divisions.The total number of pulses in the pulse width conversion section can be reduced, and the circuit configuration and memory configuration can be simplified, making the device inexpensive. It is possible to configure.

Also, in this example, the characteristics of ink sheet A with high coloring characteristics are described as being close to those of ink sheet B with low coloring characteristics, but the opposite can be achieved by controlling the voltage applied to the thermal head for each ink sheet. It goes without saying that it is also possible to bring the characteristics of ink sheet B, which has low coloring properties, closer to the characteristics of ink sheet A, which has high coloring properties. This reduces the amount of data transferred to the thermal head, and in combination with high-speed data transfer due to a reduction in the amount of data transferred to the thermal head, high-speed recording becomes possible.

Effects of the Invention The present invention provides the following effects.

(i) During multi-color ink sheet recording, each saturation density recording pulse width region can have the same current application time and the same minimum number of divided pulses.

(ii) The total number of pulses of the pulse width converter can be kept to the necessary minimum, the circuit configuration and memory configuration of the pulse width converter can be simplified, and the device can be configured at low cost.

(iii) High-speed recording is also possible by shortening the saturation density recording pulse width, that is, the recording time, of each ink sheet of multiple colors, and by reducing the amount of data transferred to the thermal head, resulting in high-speed data transfer.

[Brief explanation of the drawing]

Fig. 1 is a block configuration diagram of the main parts of a conventional thermal transfer recording device, Fig. 2 is a characteristic diagram showing the color development characteristics of the energization time and recording density of multiple color ink sheets A and B in the same thermal transfer recording device, and Fig. 3 , FIG. 4 is a characteristic diagram showing the color development characteristics of ink sheets A and B when divided by the minimum division pulse width of the thermal transfer recording device, and FIG. 5 is a characteristic diagram of the thermal transfer recording device showing an embodiment of the present invention. The block diagram, FIGS. 6 and 7 are characteristic diagrams showing the coloring characteristics of ink sheets A and B, respectively, produced by the same thermal transfer recording apparatus. 1...Pulse width converter, 2...Thermal head, 3...Fixed output power supply, 4...Variable output power supply,
5...Power control section.

Claims (1)

[Scope of Claims] 1. A thermal transfer color recording device that performs printing by mounting an ink ribbon coated with ink of multiple colors, comprising: a thermal head having a plurality of heating elements; and a thermal head that applies an electric current to the heating element of the thermal head. Voltage changing means for changing the voltage depending on the color of the ink to be printed, and a signal for determining the voltage application time to the heating element of the thermal head according to the pixel density to be printed by the thermal head to which color. pulse signal generating means for generating a pulse signal at the same time; and means for applying the voltage from the voltage changing means to the heating element of the thermal head for a time determined by the signal generated by the pulse signal generating means; A thermal transfer color recording device comprising: